More than 4 in 10 US people live in areas with unhealthy levels of ozone. The San Joaquin Valley (SJV) is a hot spot of high ozone exposures. Four of the top 7 most ozone polluted cities in the US are in the SJV where ozone affects more than 1 million children. Ozone exposure during childhood alters lung growth – even healthy young adults from high ozone environments have decreased lung function – yet the mechanisms are little understood. Much research has focused on ozone exacerbation of asthma. Dr. Van Winkle and her team are trying to develop a better understanding of how early life exposure to ozone alters normal lung development. Specifically, the researchers will measure growth in a specific region of the lung, the alveoli, using an animal model and will also determine how ozone exposure early in life alters the growth of alveoli.